PSP coverage tests fail to build on the MCP750/VxWorks 6.9 target

[jphickey]

Describe the bug
When building for MCP750 with all unit/coverage tests enabled, an error occurs:

In file included from /home/jphickey/cfecfs/github/psp/fsw/mcp750-vxworks/src/cfe_psp_exception.c:46:
/home/jphickey/cfecfs/github/psp/unit-test-coverage/ut-stubs/override_inc/arch/ppc/vxPpcLib.h:32:1: error: "_PPC_FPSCR_UE" redefined
In file included from /opt/WindRiver/vxworks-6.9/target/h/types/vxArch.h:148,
                 from /opt/WindRiver/vxworks-6.9/target/h/types/vxANSI.h:65,
                 from /opt/WindRiver/vxworks-6.9/target/h/limits.h:42,
                 from /opt/WindRiver/gnu/4.3.3-vxworks-6.9/x86-linux2/bin/../../lib/gcc/powerpc-wrs-vxworks/4.3.3/include-fixed/limits.h:122,
                 from /opt/WindRiver/gnu/4.3.3-vxworks-6.9/x86-linux2/bin/../../lib/gcc/powerpc-wrs-vxworks/4.3.3/include-fixed/syslimits.h:7,
                 from /opt/WindRiver/gnu/4.3.3-vxworks-6.9/x86-linux2/bin/../../lib/gcc/powerpc-wrs-vxworks/4.3.3/include-fixed/limits.h:11,
                 from /home/jphickey/cfecfs/github/psp/unit-test-coverage/ut-stubs/inc/PCS_basetypes.h:26,
                 from /home/jphickey/cfecfs/github/psp/unit-test-coverage/ut-stubs/inc/PCS_stdio.h:5,
                 from /home/jphickey/cfecfs/github/psp/unit-test-coverage/ut-stubs/override_inc/stdio.h:15,
                 from /home/jphickey/cfecfs/github/psp/fsw/mcp750-vxworks/src/cfe_psp_exception.c:39:
/opt/WindRiver/vxworks-6.9/target/h/arch/ppc/archPpc.h:187:1: error: this is the location of the previous definition

To Reproduce
Prepare using make SIMULATION=ppc-vxworks6.9 ENABLE_UNIT_TESTS=true prep and sample_defs config
Then run make

Expected behavior
Build should succeed

System observed on:
gs582w-cfelnx build machine with MCP750 target

Reporter Info
Joseph Hickey, Vantage Systems, Inc.

[jphickey]

Dug into this - cause is that there is a conflict/duplication between system-provided macro definitions and the macro definitions that are being intentionally overridden by the coverage test environment.

• Coverage test environment overrides most system headers, but intentionally does _not_override limits.h or stdint.h because limit macros and fixed-width types need to be correct for the machine actually executing the coverage tests.
• But the VxWorks limit.h header implicitly - through a network of nested includes - includes a whole bunch of CPU-specific definitions, including e.g. _PPC_FPSCR_UE in this case.